Computer Spiele car
Select the "Options" tab at the main menu. Then, press X, Up, X, Up, X, Up. The Computer Spiele car will now be available in the garage in Quick Play mode.

Disney XD car
Select the "Options" tab at the main menu. Then, press X, Down, X, Down, X, Down. The Disney XD car will now be available in the garage in Quick Play mode.

Achievements
Complete the following achievements to unlock Xbox Live Gamerscore points.
Winner (20 points): Win a round of the Season Championship.
Qualifier (10 points): Qualify for the first round of the Season Championship.
Survivor (25 points): Complete round six of the Season Championship.
Made The Podium (40 points): Complete the Season Championship.
Season Champion (80 points): Complete the Season Championship in first place.
Perfection (130 points): Complete every event and Season Championship race in first place.
Right On Track (10 points): Win your first Bonus Round.
Moving Ahead (25 points): Win 6 Bonus Rounds.
Leading The Way (50 points): Win every Bonus Round.
Race Winner (10 points): Win your first Race event.
Eliminator (10 points): Win your first Elimination event.
Power Up (5 points): Trigger your first Level 1 Power Play.
I Have The Power (5 points): Trigger your first Level 2 Power Play.
Heavyweight (25 points): Wreck 1000 rivals with Power Plays.
High Five (25 points): Spend a total of five minutes airborne.
Great Explorer (30 points): Trigger a total of 50 route changer Power Plays.
Going The Distance (30 points): Drive a total of 1,081 miles.
The Time Is Right (10 points): Win your first Season Detonator event.
Beat The Team (25 points): Beat 1 minute 7 seconds on Construction Site in Detonator.
Beat The Team II: The Revenge (25 points): Beat 1 minute 18 seconds on Power Plant in Detonator.
Keep On Truckin' (10 points): Win your first Season Survival event.
On The Run (10 points): Win your first Season Air Strike event.
Clear Skies (10 points): Win your first Season Air Revenge event.
Start Me Up (10 points): Win an online event.
In Good Form (10 points): Get an online form of 75 or better.
Out Of Reach (25 points): Get an online form of 25 or better.
World Beater (50 points): Get an online form of 1.
Giant Killer (25 points): Beat an opponent with an online form of 10 or better.

Additionally there are eighteen secret achievements.
Untouchable (10 points): Win a Race event without crashing.
Split/Second (10 points): Win a Race event by less than a second.
Eliminator Efficiency (10 points): Win a Season Elimination event by being in 1st place at each elimination.
Rope A Dope (10 points): With 5 seconds or less on the clock, escape from last place and certain elimination.
Follow Me (15 points): In an event, change the track twice with a Route Changer Power Play.
Bully (20 points): In an event, wreck every rival with a Power Play.
Cheapskate (10 points): Use a shortcut that a rival has triggered.
Better Luck Next Time (0 points): Get wrecked by a shortcut that a rival has triggered.
Zero To Hero (20 points): Use a route changer to go from 8th to 1st place.
Frequent Flyer (20 points): In an event, wreck 3 rivals by crash landing a plane.
Swept Away (20 points): In an event, wreck 3 rivals by destroying a dam.
The Pain Train (20 points): In an event, wreck 3 rivals by derailing a train.
Shipwrecked (20 points): In an event, wreck 3 rivals by launching a ship sideways across the track.
High Pipe (20 points): In an event, wreck 3 rivals by demolishing a cooling tower.
Convoy (25 points): Overtake 12 trucks in row without crashing in a Survival event.
Fearless (10 points): Overtake 5 trucks in a row during Sudden Death in a Survival event.
Once, twice, three times evasive (10 points): Get three Perfect Waves in a row in either an Air Strike or Air Revenge event.
Team BlackRock (10 points): Beat a member of the development team or someone who has beaten them.